Key Cutting With A CNC Mill


Keys cost like what, $2 to copy at a locksmith? But where’s the fun in that? Here’s an easy way to cut your own keys using a CNC mill!

[Bolsterman] now “works” for a real estate company that rents out various properties. Whenever someone moves out, the locks need to be changed ASAP. They use Schlage locks, which can be re-keyed to any pin combination. New keys are typically cut with a punch or a key cutting machine — he actually had one years ago, but got rid of it. Not wanting to buy a new one for his new job at the real estate company, he decided to see how hard it would be to turn his small desktop CNC into his own personal key cutting machine.

All it took for [Bolsterman] to turn his mill into a key cutting machine was a 3/8th 90° countersink bit with the end ground to a flat approximately 0.055″ across (0.035″ is the width of a factory key, but a bit of leeway makes it easier to make the key). Then you simply zero the mill off of the shoulder of the key, and using the handy Schlage pin chart (included in the original link), cut the grooves!

To automate all of this, [Torrie Fischer] created a python script for generating the GCode  for keys based on [Bolsterman’s] technique — it’s hosted over at Noisebridge’s Wiki — check it out!

But if all that seems like too much effort, you could just print a new key instead…

24 thoughts on “Key Cutting With A CNC Mill

      1. They’re around £4 where I live. They managed to botch the cut first time round, then were adamant it wasn’t possible for the machine to make a mistake like that. Until I pointed out the peak where the valley was supposed to be.

        It works now, but not without having to lift the key within the plug.

  1. Why not just install Kwikset Smartkey locks? All you need to re-key them is the key that currently works the lock, the re-keying tool and the key you want to change the lock to.

        1. Also from the article you cited:

          “There is a significant false sense of security that goes along with the locks, based at least partially upon the Grade 1 security certification for residential use awarded by the Builders Hardware Manufacturers Association (BHMA)… Part of the certification demands that the lock be able to withstand 300 pounds-force-inch of torque”

          Do you know how easy it is to generate 100 in/lbs of force with a breaker bar in the 12″-18″ range? It doesnt take that much effort at all to generate 1,800 in/lbs with a 18″ torque wrench I have.

      1. You can open a Yale lock with a paper clip its super easy and I have done it.

        The paperclip goes right to the back of the cylinder and turns the piece of metal that retracts the bolt completely ignores the pins at least with the kwikset you have to break something.

      1. 1) Aquire DNA
        2) Grow clone
        3) Fingerprint clone
        4) Realise you can just send the clone to steal their stuff
        5) Profit!
        6) Send clone to work in your salt mine
        7) More profit!

          1. I’d considered the fingerprint problem, and I’ll let you know how it turns out when my clone of Bill Gates is done.

            If it does in fact turn out fingerprints aren’t set by your genes, does anyone have any tips for makes someone look old beyond their years?

            I’m trying to avoid the ‘Say Bill, you’re looking good these days’ bit from security. Maybe I’ll wait for those anti-aging trials to start.

  2. This is a manual mill not a CNC machine. If he had a script hat automatically cut a keys numbers into a blank at the click of a mouse that would be a CNC. Bonus points for using a 2D or 3D photo of the key to make the copy from.

  3. If you have a CNC machine, you have to be careful with brass, bronze and copper. The leave very fine powder that penetrates all the little nooks and crannys of CNC machines. To avoid problems do very frequent cleaning, but not with compressed air. Compressed air should NEVER be used to clean a CNC machine that machines bronze, brass or copper since it will send the powder all over the machine and end up blocking sensors, rulers the machine.

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